diff --git a/tailbone/forms2/core.py b/tailbone/forms2/core.py
index a23470c7..f3a3cae7 100644
--- a/tailbone/forms2/core.py
+++ b/tailbone/forms2/core.py
@@ -67,6 +67,31 @@ def get_association_proxy(mapper, field):
             return desc
 
 
+def get_association_proxy_target(inspector, field):
+    """
+    Returns the property on the main class, which represents the "target"
+    for the given association proxy field name.  Typically this will refer
+    to the "extension" model class.
+    """
+    proxy = get_association_proxy(inspector, field)
+    if proxy:
+        proxy_target = inspector.get_property(proxy.target_collection)
+        if isinstance(proxy_target, orm.RelationshipProperty) and not proxy_target.uselist:
+            return proxy_target
+
+
+def get_association_proxy_column(inspector, field):
+    """
+    Returns the property on the proxy target class, for the column which is
+    reflected by the proxy.
+    """
+    proxy_target = get_association_proxy_target(inspector, field)
+    if proxy_target:
+        prop = proxy_target.mapper.get_property(field)
+        if isinstance(prop, orm.ColumnProperty) and isinstance(prop.columns[0], sa.Column):
+            return prop
+
+
 class CustomSchemaNode(SQLAlchemySchemaNode):
 
     def association_proxy(self, field):
@@ -344,21 +369,31 @@ class Form(object):
         if not self.model_class:
             raise ValueError("Must define model_class to use make_renderers()")
 
-        mapper = orm.class_mapper(self.model_class)
+        inspector = sa.inspect(self.model_class)
         renderers = {}
 
-        for field in self.fields:
-            if mapper.has_property(field):
-                prop = mapper.get_property(field)
-                if isinstance(prop, orm.ColumnProperty):
-                    if len(prop.columns) == 1:
-                        column = prop.columns[0]
+        # TODO: clearly this should be leaner...
 
-                        if isinstance(column.type, sa.DateTime):
-                            renderers[field] = self.render_datetime
+        # first look at regular column fields
+        for prop in inspector.iterate_properties:
+            if isinstance(prop, orm.ColumnProperty):
+                if len(prop.columns) == 1:
+                    column = prop.columns[0]
+                    if isinstance(column.type, sa.DateTime):
+                        renderers[prop.key] = self.render_datetime
+                    elif isinstance(column.type, sa.Boolean):
+                        renderers[prop.key] = self.render_boolean
 
-                        elif isinstance(column.type, sa.Boolean):
-                            renderers[field] = self.render_boolean
+        # then look at association proxy fields
+        for key, desc in inspector.all_orm_descriptors.items():
+            if desc.extension_type == ASSOCIATION_PROXY:
+                prop = get_association_proxy_column(inspector, key)
+                if prop:
+                    column = prop.columns[0]
+                    if isinstance(column.type, sa.DateTime):
+                        renderers[key] = self.render_datetime
+                    elif isinstance(column.type, sa.Boolean):
+                        renderers[key] = self.render_boolean
 
         return renderers